VM: Speed up output of UTF8 for 1-byte strings.

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 21191 matching lines @@
     result = OneByteString::New(length, space);
   } else {
     result = TwoByteString::New(length, space);
   }
   String::Copy(result, 0, str, begin_index, length);
   return result.raw();
 }
 
 
 const char* String::ToCString() const {
-  if (IsOneByteString()) {
-    // Quick conversion if OneByteString contains only ASCII characters.
-    intptr_t len = Length();
-    if (len == 0) {
-      return "";
-    }
-    Zone* zone = Thread::Current()->zone();
-    uint8_t* result = zone->Alloc<uint8_t>(len + 1);
-    NoSafepointScope no_safepoint;
-    const uint8_t* original_str = OneByteString::CharAddr(*this, 0);
-    for (intptr_t i = 0; i < len; i++) {
-      if (original_str[i] <= Utf8::kMaxOneByteChar) {
-        result[i] = original_str[i];
-      } else {
-        len = -1;
-        break;
-      }
-    }
-    if (len > 0) {
-      result[len] = 0;
-      return reinterpret_cast<const char*>(result);
-    }
-  }
+  NoSafepointScope no_safepoint;
   const intptr_t len = Utf8::Length(*this);
   Zone* zone = Thread::Current()->zone();
   uint8_t* result = zone->Alloc<uint8_t>(len + 1);
   ToUTF8(result, len);
   result[len] = 0;
   return reinterpret_cast<const char*>(result);
 }
 
 
 void String::ToUTF8(uint8_t* utf8_array, intptr_t array_len) const {
@@ skipping 2391 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart